1. Field of Invention
This invention relates to archery, particularly to an improved arrow which can be compacted to a smaller size and opened to full size rapidly and easily.
2. Discussion of Prior Art
Arrows have been known for millenia. The history of their development has been in the direction of arrows that shoot farther, faster, and with greater accuracy. Modern arrow technology has tried to advance these performance goals by the following expedients:
(1) LOWER WEIGHT. By lowering their weight, arrows can be made to shoot faster and travel farther. The use of modern aluminum alloys and glass/resin combinations has allowed arrow makers to produce small diameter, tubular shafts that are lightweight, but are still quite stiff and strong. PA0 (2) SMALLER DIAMETER. An arrow shaft with a smaller, more uniform diameter is lighter and more aerodynamic, and is, therefore, faster and has a greater range, than an arrow shaft with a larger, less uniform diameter. It is more aerodynamic because it has a smaller cross-section and less surface area. PA0 (3) INCREASED STIFFNESS OR "SPINE". The spine of an arrow shaft is defined by Easton Aluminum as the measured deflection, in inches, of a shaft of a given length when depressed by a 879.7 gram weight at its center. It is very desirable that an arrow have a stiff spine because upon release of the bowstring, the force of the string acting upon the inertia of the arrow causes it to flex or deflect. If this deflection is excessive, the arrow will "fishtail", causing loss of both speed and accuracy. Unfortunately, increased spine is usually attained by increasing the arrow's diameter, but increasing the diameter results in a heavier, less aerodynamic and, consequently, slower arrow. Therefore, modern arrows use tubular shafts of high strength aluminum alloys or glass/resin combinations to maximize spine for the smallest practicable diameter, wall thickness, and weight. PA0 (4) STRAIGHTNESS. This is an extremely important attribute of an arrow and results in greater accuracy. Modern arrow shaft producers use very sophisticated technology to insure maximum straightness or "trueness". PA0 (5) CORRECT BALANCE POINT. The balance point of the arrow is a very important contributing factor to its proper flight and accuracy. According to Easton Aluminum, balance point for a target arrow is from 7% to 9% of the shaft's length, measured in front of the center point (F.O.C.) of the arrow's shaft. In a bow hunting arrow, the balance point can be slightly forward of the 7% to 9% F.O.C. PA0 (1) Palma's telescoping arrow is constructed of two shaft sections, with a smaller diameter shaft section in the front end that abruptly changes to a larger diameter shaft section in the rear end. The conventional arrow has a uniform diameter throughout its entire length, which is the shape that has proven itself through millenia of use to be ideal. PA0 (2) All modern bows use some sort of arrow rest. The arrow rides along this rest as it is being propelled forward by the bowstring. Any abrupt change in the diameter of the shaft will deflect the arrow far off the intended course. The abrupt change in the diameter of the shaft of Palma's arrow makes it practically impossible to use his arrow with bows having an arrow rest. PA0 (3) Palma's telescoping arrow is much heavier than a conventional arrow due to its larger rear shaft section and its numerous parts. PA0 (4) The balance point of Palma's telescoping arrow is in the rear half of the arrow, whereas the balance point of the conventional arrow is in the front half. PA0 (5) The spine of Palms's telescoping arrow is not uniform because its front and rear shaft sections have different diameters. The conventional arrow has a uniform spine because its shaft has a uniform diameter. PA0 (6) There will be wobble between the front and rear shaft sections of Palma's telescoping arrow because of the manner in which the front shaft section is supported by the rear shaft section. This potential wobble will have an adverse effect on the straightness or "trueness" of this telescoping arrow. A conventional arrow can not have this type of wobble because the shaft is in one piece. PA0 (1) to provide an arrow which is compactible for storage, carrying, and handling; PA0 (2) to provide an arrow which can be quickly "snapped" together and joined into an extended ready position for shooting with a bow; PA0 (3) to provide a compactible, folding arrow which has a performance that is comparable with or, in some respects is better than a conventional one-piece arrow of the same diameter and length.
The above performance goals of a modern arrow have been attained at some difficulty, through the use of sophisticated engineering, modern materials, and accumulated experience of many generations.
I have found that another desirable feature is compactibility. If an arrow could be made compactible, an archer could store, carry, and handle arrows in ways that are not possible with traditional, one-piece arrows. This is because most arrows are about 24" to 34" long and thus are quite awkward to handle, store, and carry when target shooting, hunting, etc., as well as when travelling to these activities. Because the emphasis in modern arrow technology has been on increased spine and straightness with smaller diameter shafts, little experimentation, research, or consideration has been given to compactibility. It was assumed by those knowledgable in the field that an articulated arrow shaft would have too much wobble (lack straightness or "trueness") to have the accuracy required of the best modern archery arrows.
A previous attempt to create a compactible arrow is shown in U.S. Pat. No. 3,759,519 to Palma, Sept. 8, 1973. This arrow has a front shaft section which telescopes into a rear shaft section. Palma's telescoping arrow is inferior to conventional, one-piece arrows for the following reasons:
The above comparison shows that Palma's telescoping arrow is far inferior to a conventional, one-piece arrow. Most archers, and in particular bow hunters, would find it very useful to have a compactible arrow, but only if that arrow had a performance potential that is at least comparable with a conventional arrow of the same diameter and length.